How to Safely Unroot Galaxy S6 & S6 Edge, Restore back to Stock andable to get an OTA software update again

Here's how to safely unroot the Samsung Galaxy S6 and Galaxy S6 Edge and then restore it back to its official stock firmware. If you have a rooted Galaxy S6 there is a tendency and may cause the latest Firmware Over-The-Air (OTA) update to fail and sending you an error message that say something like "The operating system on your device has been modified in an unauthorized way. Try downloading software updates using Smart Switch on your computer or visit a customer service center."

Sometimes it will also cause soft-bricks such as bootloop, the phone keeps restarting and won't pass the Samsung welcome screen, the phone froze and stuck at Samsung and carrier logo and other problems. So that means if you want to stay out of trouble when you want to get the latest firmware version you must fully remove root and unroot your Galaxy S6 first. To unroot the Galaxy S6 is easy on some part but keep in mind that there are some safety procedures that you may need to consider before you unroot the Galaxy S6 so it won't end up into undesirable outcomes.

This Galaxy S6 how to unroot guide covers on the following variants; such as the international Galaxy S6 SM-G920F, T-Mobile Galaxy S6 SM-G920T, Sprint Galaxy S6 SM-G920V, Canadian Galaxy S6 SM-G920W8 from Bell, Rogers, Telus and other carriers, Galaxy S6 SM-G920I version from Australia, Singapore, India & Latin America. I only covered the mentioned Samsung Galaxy S6 variants since these devices can be easily rooted. This does not include and cannot be applied on Verizon Galaxy S6 SM-G920V and AT&T Galaxy S6 SM-G920A since these variants are mostly has a locked bootloader. So I set aside and separate the unroot guides for the two.

If your Samsung Galaxy S6 is rooted with "CF-Auto Root" and have had a SuperSU installed. Right after CF-Auto Root installation it is actually already have the 'SuperSU' app installed in the device. The good thing is; CF-Auto Root also built with an option to permanently remove root in the app itself. So if you just simply want to remove root then follow these steps.

To activate the "SuperSU" unroot option just follow these steps:
  1. From Home screen, tap Apps then find the SuperSu app .
  2. Once in SuperSU screen, tap the Settings tab.
  3. Scroll down and locate option labeled Full unroot. A warning message will then pop-up, just tap on the Continue button.
  4. Wait until it says uninstalling root and then the phone automatically reboots. You can also manually restart the phone by pressing the Power button for about 10 seconds.

However, the process above does technically removed the root or the superuser access to the device but it doesn't mean that it is safe now to run and perform the "OTA Software Update" again. Yes, the Galaxy S6 is unrooted at this stage but the device status still set into custom. This means the device still in modified status and the software update cannot get through when and if we tried to perform Software update it will still says "The operating system on your device has been modified in an unauthorized way. Try downloading software updates using Smart Switch on your computer or visit a customer service center." So the best way to unroot your Galaxy S6 is by restoring back its custom status to official. Doing so you will get the latest Software update again without any difficulties. This method will wipe out any modification you have made in your Galaxy S6, even you do have custom recovery and modified kernels installed.

Here's what it looks like on a modified Galaxy S6 status of which can be viewed in the device "Download mode" screen.
Product name: SM-G920F
 Current BINARY: Custom
 System Status: Custom
 Reactivation LOCK: OFF
 Secure Download: Disabled
 Kernel RP SWREV: 1

Anyway, to access the Galaxy S6 in download mode, you may just press the (Volume Down, Home and Power button) then followed by pressing the (Volume Up) button. As long as your Galaxy S6 shows that information you won't be able to get the official software update again. You must need to reset that system status from custom to official so that the Software update can get through without any hiccups, such as this;
Product name: SM-G920F
Current BINARY: Samsung official
System Status: Official
Reactivation LOCK: OFF
Secure Download: Disabled
Kernel RP SWREV: 1

So, how to safely unroot Samsung Galaxy S6 and might as well also restore back to official status?
There are two effective method to unroot the Samsung Galaxy S6 either you may use the Smart Switch or by means of flashing back the official stock firmware directly into the device.

Unroot Samsung Galaxy S6 and restore back to official stock firmware using Smart Switch (First Method)

Using Samsung's owned app called "Smart Switch" that allows Galaxy S6 users to back up and transfer files but it also capable for restoring the Galaxy S6 official firmware. The Smart Switch is the replacement of Samsung's "Kies" that can be use on Galaxy S6 and latest Samsung Android devices. We are going to use the Smart switch apps that can be installed on both Windows and Mac computers. Though this method will work to unroot the Samsung Galaxy S6 but sometimes it will fail as depends how your Galaxy S6 being modified. But you may try this method first, unless we still have a the second method down below.

Download Smart Switch:

Smart Switch for PC and Mac

Run Smart Switch as administrator once installed in your computer . Then simply connect your Galaxy S6. Click "Backup" icon to back up your important data first and foremost such as Contacts, Messages, Call Log, Videos, Music, Photos, Application and etc.

Click on More... option, once the backup has made. Choose "Emergency software recovery and initialization." in the drop-down.

Select "Software Update and Initialization" tab.

Follow the on-screen instructions that ask you to proceed or cancel.
Then wait until it says Software update and Initialization are complete.

Once your Galaxy S6 reboots disconnect and disconnect the USB data cable. Then lastly restore the previously back-up files by clicking the "Restore" icon.

However, if the Smart Switch method fail , you can try the second method below. The process is something similar to the above equation but this time around we are going to forcefully and directly install back the official firmware on our Galaxy S6.

Fully Unroot Samsung Galaxy S6 and Galaxy S6 Edge by Restoring back the Original and Official Stock firmware

This has been a proven method to fully remove root and any modification that has been made into the Galaxy S6 or Galaxy S6 edge. No matter it runs on any non-official firmware build, custom recovery and custom kernel it will all cleaned-up using this process.

Read the Safety Guidelines: How to Install Galaxy S6, S6 Edge & S6 edge+ Stock Firmware